Method and apparatus for a low profile fuel tank cap assembly

ABSTRACT

In providing a fuel tank cap assembly for a fuel tank for an off-road motor vehicle, a vent assembly is first attached to the fuel tank. Second, a fuel supply port is constructed in the fuel tank. Next, a sleeve portion is secured to the fuel supply port. Finally, a cap portion is inserted into the sleeve portion. The fuel tank cap assembly comprises a vent assembly attached to the fuel tank, a fuel supply port constructed in the fuel tank, a sleeve portion secured to the fuel supply port, and a cap portion inserted into the sleeve portion. Alternatively, a fuel tank contains the fuel tank cap assembly.

CROSS-REFERENCES TO RELATED APPLICATIONS

Not Applicable

FEDERALLY SPONSOR RESEARCH OR DEVELOPMENT

Not Applicable

SEQUENCE LISTING, TABLE, OR COMPUTER LISTING

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a fuel tank closure system for a motor vehicle. More particularly, the invention relates to a method and an apparatus for a low-profile fuel tank cap assembly for an off-road motor vehicle, such as a dirt bike or an all terrain vehicle (ATV).

2. Description of the Related Art

Motor vehicles, such as a motorcycle, generally incorporate a fuel tank for storing fuel which is supplied to run an engine to provide power to the vehicle. The motorcycle fuel tank is filled through a fuel supply port, an opening typically in the form of a neck or bung, at the upper end of the fuel tank. The supply port opening is closed by a fuel tank closure device. In general, a motorcycle incorporates a body frame on which the engine is mounted, with the fuel tank mounted above the engine. Usually, a driver's seat is disposed to the rear of the fuel tank. The fuel supply port is typically formed in the upper surface of the fuel tank. The fuel supply port is closed and sealed by the tank closure device, which typically is in the form of a fuel tank cap.

Numerous fuel tank cap assemblies are known in the art. Fuel tanks on motorcycles are typically filled though an opening in the top and front of the fuel tank. Motorcycle fuel tank caps often extend above the outer surface of the fuel tank, in order to be grasped for the purpose of being tightened or loosened. For motorcycles such as those known as street bikes, a fuel tank cap extending upwards tends to be considered unsightly, not conforming to the aesthetically smooth lines of the vehicle in general and the fuel tank in particular. It is therefore desirable to have a fuel tank closure device for street bikes which may sit substantially flush with the outer surface of the fuel tank.

However, there are other motor vehicles known as off-road motor vehicles. These would include motorcycles such as dirt bikes, mini-bikes, pocket bikes and related motor vehicles such as all terrain vehicles (ATV's), also known as 4 wheelers, all well known in the art. For off-road motor vehicles, a fuel tank cap extending upwards is much more than an unsightly blemish—it is a safety hazard. Off-road motor vehicles are commonly raced over very rough terrain, making for a very rough ride. Riders of off-road motor vehicles ride forward on the driver seats and even on top of the fuel tank to gain greater control in the vigorous turns and jumps commonly associated with riding such vehicles. Unfortunately, such rough riding often leads to sudden inadvertent stops, such as when a rider hits an obstacle, falls forward, or hits another rider. During these extreme decelerations, which happen all too frequently, the rider's momentum carries the entire body weight forward, to only be stopped by the fuel tank cap and neck. Due to the rider's body position relative to the protruding fuel cap, these accidents commonly lead to serious groin injuries.

Two factors further exacerbate the danger. First, the fuel tank cap assemblies of off-road motor vehicles typically include a vent tube nipple and line further protruding above the fuel tank. Thus, the target for an unfortunate rider sliding forward off the driver seat onto the fuel tank, either purposely or accidentally, is even greater than just the fuel cap itself. Second, the evolution over the past decade has seen the driver seats of off-road motor vehicles getting flatter to promote the advantage of the rider's weight distribution on all areas of the vehicle to create greater control. But the solution of the control problem only worsens the protruding fuel tank cap problem. Making the off-road motor vehicle easier to move around on magnifies the problem of the riders' weight slamming forward and being stopped by the fuel tank cap. This problem has yet to be addressed.

Street bikes have had flush mount fuel tank caps for several years now. The reason for this was aesthetics and not safety. These caps have a vent incorporated and are locking gas caps which are opened with a key and designed to complement the aggressive lines of today's motorcycles. Safety for the street bike fuel caps was never a concern because the caps are situated in the top middle part of the tank. On these applications the fuel lid is several inches above the groin area of the rider and the body would have to crush the fuel tank in about 8 inches to even reach the cap. Thus, the aesthetics of the fuel tank is the major concern for street bikes.

For example, Hotch, Matthew Jon, U.S. Pat. No. 6,648,160 B2, “Flush Fuel Cap”, issued Nov. 18, 2003 discloses a flush-fitting fuel tank cap, primarily for a street motorcycle. The cap primarily comprises a cylindrical portion that may screw into a threaded gasoline tank neck and a handle to rotate the cylindrical portion. The handle is movable between an up (open) and down (closed) position. The cap fits flush with the outer surface of the gas tank when closed, but the cap can be easily removed by rotating when open. In particular, the cap is designed to always return to the same original position when closed, so that the orientation of painted patterns incorporating the finished surfaces of the cap and the fuel tank may be maintained. Using a different material for the fuel tank cap would create an undesirable appearance on today's street bikes with their flowing lines and custom paint. By making the fuel tank cap completely flat and of the same material as the fuel tank, the cap could be painted into the paint scheme of the bike. As well as eliminating the key, this cap would incorporate a vent internally in the cap and it would still look appealing.

However, in the Hotch U.S. Pat. No. 6,648,160 patent, the flush fit of the fuel cap is purely for aesthetic purposes, not for the safety of the rider. The only safety concerns addressed are the venting of gasses from the fuel tank and the prevention of spilling of liquid fuel from the fuel tank, by the provision of washers or gaskets. Because all dirt bikes and ATV's have molded plastic tanks on them, of the color from the manufacture, they use no paint. Thus this aesthetic concern does not even arise for dirt bikes and ATV's. The purpose of the Hotch U.S. Pat. No. 6,648,160 patent is solving the undesirable looks of the manufactures fuel tank caps on street bikes.

Similarly, Jansson, Erik Tommy, U.S. Pat. No. 6,209,745 B1, “Pop Up Flush-Mount Gas Cap”, Issued Apr. 3, 2001 discloses a flush-fitting fuel tank cap, primarily for street motorcycles and powerboats. The cap is opened by unseating a pop-up mechanism which is connected to a lid which is displaced to unscrew a sealing cap from the fuel tank. Again, the flush fit of the cap to the fuel tank surface is purely for aesthetic purposes, not for the safety of the rider.

Flush-fitting fuel tank caps for dirt bikes are provided as part of quick fill fueling systems. One example is the quick-fill system offered by IMS Racing Products Corp. A conventional fuel tank cap is replaced by an assembly having a movable plunger that is normally spring biased in a closed position and that provides access to the fuel tank when the plunger is depressed. Conventional refueling is no longer possible since dispensing fuel requires a special fuel container. Installation of the system requires extensive and permanent modification of the fuel tank or replacement and installation of a custom-made fuel tank.

Thus, a need exists for a fuel tank closure device that protects the rider of a off-road motor vehicle from injury due to sliding into a protruding fuel tank cap or vent line. Thus, a need exists for a fuel tank filler cap for an off-road motor vehicle that has a low profile or is substantially flush fitted to the surface of the fuel tank for safety.

BRIEF SUMMARY OF THE INVENTION

The invention is a method and an apparatus for providing a fuel tank cap assembly for a fuel tank for an off-road motor vehicle. In a method embodiment, a vent assembly is first attached to the fuel tank. Second, a fuel supply port is constructed in the fuel tank. Next, a sleeve portion is secured to the fuel supply port. Finally, a cap portion is inserted into the sleeve portion.

In an apparatus embodiment, the fuel tank cap assembly comprises a vent assembly attached to the fuel tank, a fuel supply port constructed in the fuel tank, a sleeve portion secured to the fuel supply port, and a cap portion inserted into the sleeve portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and its advantages may be more easily understood by reference to the following detailed description and the attached drawings, in which:

FIG. 1 is a flowchart illustrating the steps of an embodiment of the method of the invention for providing a low profile fuel tank cap assembly;

FIG. 2 is an elevation view of an embodiment of the invention for a sleeve portion of a low profile fuel tank cap assembly;

FIG. 3 is a plan view of an embodiment of the invention for a sleeve portion of a low profile fuel tank cap assembly;

FIG. 4 is an elevation view of an embodiment of the invention for a cap portion of a low profile fuel tank cap assembly;

FIG. 5 is a plan view of an embodiment of the invention for a cap portion of a low profile fuel tank cap assembly;

FIG. 6 is a sectional view of an embodiment of the invention for a low profile fuel tank cap assembly in a closed position; and

FIG. 7 is a sectional view of an embodiment of the invention for the low profile fuel tank cap assembly in an open position.

While the invention will be described in connection with its preferred embodiments, it will be understood that the invention is not limited to these. On the contrary, the invention is intended to cover all alternatives, modifications, and equivalents that may be included within the scope of the invention, as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

The invention is a method and an apparatus for a low profile fuel tank cap assembly for an off-road motor vehicle, such as a dirt bike or an ATV. The invention provides a smooth transition from driver seat to fuel tank, unencumbered by protruding fuel tank caps or vent lines. This allows the rider better control of the motor vehicle and, most importantly, greater safety in the case of accidental or controlled sudden decelerations.

In one embodiment of the method of the invention, an existing fuel tank with an existing fuel tank cap and vent line is retro-fitted to contain the low profile fuel tank cap assembly. First, the fuel tank vent line is moved to the front uppermost portion of the fuel tank. Then the existing fuel cap is removed and discarded. Next, the existing threaded spigot is sawed off a fuel tank and sanded down flat. Then, the low profile fuel tank cap assembly is mounted on the fuel tank. The low profile fuel tank cap assembly comprises two principle portions—a sleeve portion and a cap portion—that act in concert. A low profile sleeve portion is inserted in the fuel tank where the threaded spigot used to be. Finally, a cap portion is screwed into the sleeve.

Another embodiment of the invention comprises a combination of a fuel tank and the low profile fuel tank cap assembly. A fuel tank for an off-road motor vehicle can be manufactured with the low profile fuel tank gas assembly of the invention. The invention is not limited to retro-fitting the fuel tank cap assembly to existing fuel tanks, but includes the combination of the fuel tank cap assembly with fuel tanks in their original manufacture.

The low profile sleeve portion of the fuel tank cap assembly comprises an upper mounting flange and a lower hollow cylinder with a inner bore containing a recessed threaded section. The sleeve is secured to the fuel tank to have its mounting flange lying substantially flush with the outer surface of the fuel tank and ramped completely around to create a smooth transition. The cap portion of the low profile fuel tank cap assembly comprises a lid and a shaft with a threaded section. The cap portion is screwed into the sleeve so that the threaded section of the shaft mates with the threaded section of the inner bore of the sleeve. The cap is sized to fit inside the sleeve with the lid flush with the upper mounting flange.

FIGS. 1-6 show a method and an apparatus for a low profile fuel tank cap assembly having features and advantages of the present invention. FIG. 1 shows a flowchart illustrating the steps of an embodiment of the method of the invention for providing a low profile fuel tank cap assembly for an off-road motor vehicle. The low profile fuel tank cap assembly preferably comprises a sleeve portion and a cap portion. FIGS. 2 and 3 illustrate an elevation view and a plan view, respectively, of the sleeve portion, while FIGS. 4 and 5 illustrate an elevation view and a plan view, respectively, of the cap portion. FIG. 6 illustrates the combination and operation of the sleeve and cap portions of the low profile fuel tank cap assembly.

Referring to FIG. 1, at step 11, a vent assembly is inserted into the fuel tank to prevent vapor lock. In one embodiment, the vent assembly is positioned in the front uppermost portion of the fuel tank. In a preferred embodiment, the vent assembly comprises a rubber grommet inserted into a hole drilled in the fuel tank and a 90° push lock inserted into the grommet and a vent tube. In another embodiment, the existing vent assembly is moved from the fuel tank cap to the front uppermost portion of the fuel tank. The existing vent assembly typically comprises a vent nipple tube and vent line. In another embodiment, any other type of vent assembly known in the art is used, such as, for example, a check valve. In yet another embodiment, the vent assembly is contained internally within the fuel cap, as is well known in the art.

As fuel is drawn into the engine from the fuel tank during normal operation of the motor vehicle, the vent assembly allows outside air to be drawn into the fuel tank through venting orifice to relieve any vacuum that would occur in the fuel tank. As will be recognized by anyone of skill in the art, the vent assembly may be located in a number of locations in order to allow air to pass between the inside and outside of the fuel tank and is not limited to the embodiment disclosed here.

Next, at optional step 12, a fuel tank cap is removed from the fuel tank, if one is already present. The fuel tank cap may be discarded.

Next, at step 13, a fuel supply port is inserted in a fuel tank for an off-road motor vehicle. In a preferred embodiment, the fuel supply port is preferably in the form of a circular orifice in the upper end surface of the fuel tank, when mounted on the off-road motor vehicle. The circular orifice may be of different diameters depending upon the size of the off-road motor vehicle and its fuel tank, as is well known in the art. In the preferred embodiment, an existing fuel filler neck is removed from an existing fuel tank for the off-road motor vehicle. Typically this fuel filler neck is in the form of a threaded spigot or spicket. In one embodiment, the spigot is sawed off and then any remaining portions of the spigot that still protrude above the flat plane or curvature of the fuel tank are sanded down.

Next, at step 14, a low profile sleeve is inserted into the fuel supply port, preferably the circular orifice remaining from step 11. The sleeve is secured to the surface of the fuel tank by any means known in the art. In one embodiment, the sleeve is bonded to the fuel tank by epoxy, aircraft sealant, or any other appropriate adherent known in the art. In another embodiment, the sleeve is secured to the fuel tank by screws. The screws may be accompanied by pins protruding from the surface of the fuel tank and inserted into the sleeve to help prevent twisting when torque is applied. The structure of the sleeve is described in greater detail below with reference to FIGS. 2 and 3.

Finally, at step 15, a fuel cap is screwed in to the low profile sleeve inserted in step 12. To aid in screwing the fuel cap into and out of the sleeve from step 14, the fuel cap may include any type of handle known in the art. Preferably, the handles are adapted to sit flush with the top of the fuel cap when the fuel cap is completely screwed into the sleeve (the closed position) to promote the low profile design of the fuel tank cap assembly of the invention. The cap is described in greater detail below with reference to FIGS. 4 and 5.

The method of the invention as described above with reference to the flowchart in FIG. 1 allows retro-fitting the low profile fuel tank cap assembly to all past and present off-road dirt bikes and ATV's since the introduction of plastic fuel tank reservoirs, which is approximately the late 1970's. However, the invention is not just limited to a fuel tank cap assembly, as inserted in a fuel tank. Thus, in another embodiment, the invention includes a combination of a fuel tank plus the fuel tank cap assembly described here. Thus, the invention encompasses the inclusion of the fuel tank cap assembly in the original manufacture of a fuel tank for a motor vehicle.

FIGS. 2 and 3 illustrate an embodiment of the invention for the sleeve portion of a low profile fuel tank cap assembly, as discussed in step 14 of FIG. 1. FIG. 2 is an elevation view of the sleeve portion, while FIG. 3 is a plan view of the sleeve portion. In FIGS. 2 and 3, the sleeve portion is generally designated by reference numeral 20. The sleeve portion 20 preferably includes a flange section 21 and a bore section 22. The flange section 21 preferably has a larger diameter than the bore section 22. The bottom 23 of the flange section 21 is preferably situated above and fixably attached to the top 24 of the bore section 22, with the flange section 21 and the bore section 22 preferably coaxially centered. The sleeve portion 20 is preferably manufactured from stainless steel, but any suitable component materials, such as aluminum, plastic, or polymer, may be used and are not limited to those of the preferred embodiment.

The flange section 21 and the bore section 22 comprising the sleeve portion 20 are preferably machined from a single piece of metal, although the combination could also be formed by any other methods known in the art. Alternatively, the flange section 21 and the bore section 22 could be formed separately and then attached together by any means known in the art, including, but not limited to, welding, gluing, screwing, bolting, and riveting.

The flange section 21 of the sleeve portion 20 comprises a mounting flange 25 and a supporting flange 26. The bottom surface 27 of the shelf formed by the mounting flange 25 is adapted to contact and be secured to the outer surface of the fuel tank. The top surface 28 of the shelf formed by the supporting flange 26 is sized and adapted to be in contact with the cap portion of the fuel tank cap assembly. The top surface 29 of the mounting flange 25 is ramped all around the edge of its annular circumference.

The flange section 21 is adapted to be secured to the surface of the fuel tank. This will be described in greater detail below in the discussion of the fuel tank cap assembly with reference to FIG. 6, below. Securing the flange section 21 secures the entire fuel tank cap assembly to the fuel tank. The flange section 21 may be secured by any means known in the art, such as bonding. In one embodiment, the flange section 21 is secured to the fuel tank by screws. The screws may be accompanied by pins protruding from the surface of the fuel tank and inserted into the flange section 21 to help prevent twisting when torque is applied to the cap portion, discussed below with reference to FIGS. 4 and 5. In this embodiment, the flange section 21 has holes 30, preferably equally spaced around its annular circumference to accept the screws and pins, if any.

The bore section 22 of the sleeve portion 20 is preferably in the form of a hollow cylinder. An inner periphery of the bore section 22 additionally includes an internal threaded section 31 containing female threads. It will be seen with reference to the discussion of the cap portion in FIG. 3 below that the female threads of the threaded section 31 are preferably adapted such that they cooperate with and may engage with the mating male threads in a threaded section in the cap portion.

FIGS. 4 and 5 illustrate an embodiment of the invention for the cap portion of a low profile fuel tank cap assembly, as discussed in step 15 of FIG. 1. FIG. 4 is an elevation view of the cap portion, while FIG. 5 is a plan view of the cap portion. In FIGS. 4 and 5, the cap portion is generally designated by reference numeral 40. The cap portion 40 preferably includes a lid section 41 and a shaft section 42. The lid section 41 is preferably in the form of a circular disk and the shaft section 42 is preferably in the form of a cylinder. The lid section 41 preferably has a larger diameter than the shaft section 42. The bottom 43 of the lid section 41 is preferably situated above and fixably attached to the top 44 of the shaft section 42, with the lid section 41 and the shaft section 42 preferably coaxially centered. The cap portion 40 is preferably manufactured from billet aluminum, but any suitable component materials, such as steel, plastic, or polymer, may be used and are not limited to those of the preferred embodiment.

The lid section 41 and the shaft section 42 comprising the cap portion 40 are preferably machined from a single piece of metal, although the combination could also be formed by any other methods known in the art. Alternatively, the lid section 41 and the shaft section 42 could be formed separately and then attached together by any means known in the art, including, but not limited to, welding, gluing, screwing, bolting, and riveting. The lid section 41 is preferably designed to be of a suitable thickness to prevent bending or warping over time. Depending on the material used to manufacture the lid section 41, the thickness may vary as more rigid materials may have a smaller thickness than more flexible materials. The shaft section 42 is preferably in the form of a solid cylinder, although alternatively, it may be in the form of a hollow tube.

An outer periphery of the shaft section 42 of the cap portion additionally includes an external threaded section 45. The male threads of the threaded section 45 are preferably adapted such that they cooperate with and may engage with the mating female threads in the threaded section 31 on the inner periphery of the bore section 22 of the sleeve portion 20.

The shaft section 42 preferably includes a washer or gasket 46 disposed on the shaft section 42 above the threaded section 45. The washer or gasket 46 is made of a compressible material such as rubber so that when the cap portion 40 is screwed into the sleeve portion 20, the washer or gasket 46 will be compressed, thereby sealing the fuel tank from fuel leakage out of the fuel tank. The washer or gasket 46 is preferably in the form of an O-ring.

When the cap portion 40 is completely screwed into the sleeve portion 20, the top surface 47 of the lid section 41 preferably sits substantially flush relative to the top surface 29 of the flange section 21. Flush is defined here by the top surface 47 of the lid section 41 being in substantially the same plane or along the same curvature as the immediately surrounding top surface 29 of the flange section 21.

Since the top surface 47 of the lid section 41 does sit substantially flush relative to the top surface 29 of the flange section 21, applying an initial torque to the lid section 41 requires some manner of handle device to enable gripping the lid section 41 to remove the cap portion 40 from the sleeve portion 20. Illustrated as one embodiment of the invention is a handle device in the form of a slot 48 in the top surface 47 of the lid section 41. Any conveniently shaped and sized implement may be inserted into the slot 48 to apply an initial torque to raise the cap portion 40 from the sleeve section 20. However, the embodiment Illustrated is not meant to restrict the invention, which may utilize any manner of handle device known in the art. For example, a handle in the form of a fill-up tab, well known in the art, may be employed.

FIGS. 6 and 7 are sectional views of an embodiment of the invention for the low profile fuel tank cap assembly in a closed and an open position, respectively. In FIGS. 6 and 7, the fuel tank cap assembly is generally designated by reference numeral 60. The sleeve portion 20 of the assembly is positioned into an opening in the outer surface 61 of the fuel tank. The bottom surface of the shelf formed by the mounting flange is fixably coupled to the outer surface 61 of the fuel tank.

The fuel tank cap assembly operates in a simple manner, which is illustrated in FIG. 4. The shaft section 42 of the cap portion 40 is able to rotate upon applying a counter-clockwise torque to the lid section 41. Thusly, the cap portion 40 is unscrewed and removed from the sleeve portion 20 and then the fuel tank may be filled by introducing fuel in a normal fashion through the inner bore of the sleeve portion 20. When the fuel tank is filled, the cap portion 40 is screwed back into the sleeve portion 20 by applying a clockwise torque to the lid section 41. The screwed coupling is formed with the male thread of the external threaded section 45 of the cap portion 40 mating with the female thread of the internal threaded section 31 of the sleeve portion 20. The threaded engagement between the cap portion 40 and the sleeve portion 20 provides provide an air- and fuel-tight seal to prevent the fuel from leaking outside of the fuel tank.

The low profile design of the sleeve portion in combination with the cap portion results in the fuel tank cap assembly sitting substantially flush relative to the outer surface of the fuel tank. The ramped configuration of the top surface of the mounting flange results in a smooth transition from the outer surface of the fuel tank across the fuel tank cap assembly. Now instead of having a 3 inch wide and 2 inch tall hard plastic fuel cap to stop the rider's body weight at the groin area, the next nearest obstacle is the handle bar and upper tree, which are both completely padded. The design of the low profile fuel tank cap assembly, as embodied in the present invention, could eliminate almost all groin injuries in motocross, supercross, ATV racing and even pleasure riding.

Directional words such as “up,” “down”, “top”, and “bottom” are used herein to describe the relative geometry of the parts described and refer to the position the cap assumes when it is threaded into the top of an off-road motor vehicle fuel tank. Such terms and phrases are not intended to describe positions or directions relative to any frame of reference external to said parts.

For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects and advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

It should be understood that the preceding is merely a detailed description of specific embodiments of this invention and that numerous changes, modifications, and alternatives to the disclosed embodiments can be made in accordance with the disclosure here without departing from the scope of the invention. The preceding description, therefore, is not meant to limit the scope of the invention. Rather, the scope of the invention is to be determined only by the appended claims and their equivalents. 

1. A method for providing a fuel tank cap assembly for a fuel tank for an off-road motor vehicle, comprising: attaching a vent assembly to the fuel tank; constructing a fuel supply port in the fuel tank; securing a sleeve portion to the fuel supply port; and inserting a cap portion into the sleeve portion.
 2. The method of claim 2, wherein attaching a vent assembly comprises: drilling a hole in the front uppermost portion of the fuel tank; inserting a rubber grommet into the drilled hole; inserting a 90° push lock into the grommet; and inserting a vent tube onto the push lock.
 3. The method of claim 2, wherein constructing a fuel supply port comprises: sawing an existing threaded spigot off the fuel tank; and sanding any remaining spigot down flat to the fuel tank.
 4. The method of claim 2, wherein securing a sleeve portion comprises: inserting the sleeve portion into the fuel supply port; and screwing the sleeve portion to the fuel tank.
 5. The method of claim 2, wherein inserting a cap portion comprises: screwing the cap portion into the sleeve portion so that a threaded section of the cap portion engages a corresponding threaded section of the sleeve portion.
 6. A fuel tank cap assembly for a fuel tank for an off-road motor vehicle, comprising: a vent assembly attached to the fuel tank; a fuel supply port constructed in the fuel tank; a sleeve portion secured to the fuel supply port; and a cap portion inserted into the sleeve portion.
 7. The fuel tank cap assembly of claim 6, wherein the vent assembly comprises: a rubber grommet inserted into a hole drilled in the front uppermost portion of the fuel tank; a 90° push lock inserted into the grommet; and a vent tube inserted onto the push lock.
 8. The fuel tank cap assembly of claim 6, wherein the fuel supply port comprises a circular orifice in the upper end surface of the fuel tank.
 9. The fuel tank cap assembly of claim 6, wherein the sleeve portion comprises: a flange section including a mounting flange and a supporting flange; and a bore section in the form of a hollow cylinder, wherein an inner periphery of the bore section includes an internal threaded section.
 10. The fuel tank cap assembly of claim 6, wherein the cap portion comprises: a lid section in the form of a circular disk; and a shaft section in the form of a solid cylinder, wherein an outer periphery of the shaft section includes an external threaded section and an O-ring disposed on the shaft section above the threaded section.
 11. A fuel tank assembly for an off-road motor vehicle, comprising: a fuel tank; a vent assembly attached to the fuel tank; a fuel supply port constructed in the fuel tank; a sleeve portion secured to the fuel supply port; and a cap portion inserted into the sleeve portion.
 12. The fuel tank of claim 11, wherein the vent assembly comprises: a rubber grommet inserted into a hole drilled in the front uppermost portion of the fuel tank; a 90° push lock inserted into the grommet; and a vent tube inserted onto the push lock.
 13. The fuel tank of claim 11, wherein the fuel supply port comprises a circular orifice in the upper end surface of the fuel tank.
 14. The fuel tank of claim 11, wherein the sleeve portion comprises: a flange section including a mounting flange and a supporting flange; and a bore section in the form of a hollow cylinder, wherein an inner periphery of the bore section includes an internal threaded section.
 15. The fuel tank of claim 11, wherein the cap portion comprises: a lid section in the form of a circular disk; and a shaft section in the form of a solid cylinder, wherein an outer periphery of the shaft section includes an external threaded section and an O-ring disposed on the shaft section above the threaded section. 